1. Field of the Invention
The present invention relates to a control switch assembly for an air pump, and more particularly to a control switch assembly having a unidirectional valve actuatably mounted on a nozzle that is securely attached to the control switch assembly. When the control switch is deactivated, the unidirectional valve is actuated by a push rod controllably connected to the control switch. The pressure inside a diaphragm of the air pump will bleed off before the air pump starts to work to facilitate air being pumped into an object.
2. Description of Related Art
A conventional air pump has a diaphragm inside the air pump, so that with the vibration of the diaphragm, the air is pumped outside the pump. However, there is a problem concerning the diaphragm. When the compressor stops, pressure exists in the space above the diaphragm, and the pressure will apply a force on the diaphragm to stop the diaphragm from vibrating. Under such a condition, even with the mechanical assistance of a cam in the compressor, the diaphragm will not vibrate. It is noted that if the diaphragm is not able to vibrate, the air from the inlet will not be able to be pumped outside the compressor from the exhaust port. With reference to FIG. 5, a conventional air pump has a compressor (70) with two discharge ports (71, 72) with each port (71, 72) connected to a tube. One of the tubes is connected to an outlet nozzle (73) to inject air into an object, e.g. a tire, and the other tube is connected to a pressure gauge (74) so that a user is able to sense the pressure inside the object. A switch (75) controls the activation of the compressor (70), such that when the switch (75) is actuated (pressed), the compressor (70) starts and air is pumped and ejected from the compressor (70) through the outlet nozzle (73). From practical experience, persons skilled in the art know that a compressor (70) has to start before attempting to inflate an object. That is, the compressor (70) has to begin pumping air before any attempt is made to inflate the object. Otherwise, the diaphragm inside the compressor (70) will be under a pressure greater than what the compressor can handle. When the pressure exists above the diaphragm, it is impossible for the compressor to work with the current design.
In order to overcome the foregoing problems, the invention intends to provide an improved control switch assembly for an air pump to mitigate and obviate the problems existing in the current design.
The primary objective of the invention is to provide an improved control switch assembly with a unidirectional valve selectively activated by the movement of the control knob. With such an arrangement, when the control knob deactivates the compressor, the unidirectional valve allows the pressure above the diaphragm to bleed out of the compressor to facilitate the pumping of air into the object.
Another objective of the invention is to provide a second unidirectional valve in the exhaust port to ensure that the air inside the object will not flow back into the compressor to hinder the operation of the compressor and thus to smooth the outflow of air pumped by the compressor.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.